In recent years, a fuel cell (a solid polymerelectrolyte type fuel cell) employing a polymer membrane having proton conductivity as an electrolyte has been predominant as a use for a fuel cell of a power source to be mounted on vehicles and the like, since such electrolyte is operated at low temperatures, has high power density and is capable of being downsized.
A method of impregnating a polymerelectrolyte into voids of a porous substrate has been proposed as a method for giving mechanical strength, durability and the like to a polymerelectrolyte membrane (Japanese Patent Application Laid-Open No. 6-29032).
A method of dipping a porous substrate in a solution of a polymerelectrolyte, an method for applying a solution of a polymerelectrolyte to a porous substrate and the like have been proposed as a method of impregnating a polymerelectrolyte into voids of a porous substrate (Japanese Patent Application Laid-Open No. 8-329962).
However, in the above-mentioned continuous processes for producing a polymerelectrolyte membrane, for example, when a porous substrate is previously disposed on a supporting material and coated with a solution of a polymerelectrolyte, it is considered that swelling and slackening are caused on the porous substrate, and consequently wrinkling and the like are occasionally caused in appearance of a product to be obtained, resulting in deterioration external appearance.
An object of the present invention is to provide a process for continuously producing a polymerelectrolyte membrane in which wrinkling is suppressed and whose appearance is excellent.